stroker life span?

Realstically, a lot has to do with the machine work, and the life style of the engine but the point of this type of build is not longevity. A street/strip 4" stroke, properly built, should last upwards of 30-40K miles before it will start showing signs of issues. If things like bore finish are off, thinner ring stacks are used, or high rpm or heavy abuse is experienced that drops to about 15-20K at most. I've seen some of these start showing signs of ring seal going away after a few thousand miles drag engines, but that's several seasons and hundreds and hundreds of passes. A friend also has a 496 RB, mild solid roller, runs low 11s in a portly E body. He drove that car everywhere and it's got 50K miles on it. It also smokes a little now, especially when he's racing, and it's overdue for freshening. We build them for power, and with the expectation that they are not racking up the miles like a commuter car does.
The 454 example is a big block adn the side load is spread out over a large area in terms of both the ring sealing edge and the piston skirt. My experience has been whenever I tore one down with anything over 70K miles, the pistons were worn out and the bores had a lot of taper and rigde. Not a prime example of apples to apples.